I am experiencing this bug on Ubuntu 15.10 Wily, using Nvidia drivers and Gnome (not Unity, if that's the name of the touchscreen-based interface).

It appears that vlc must be spelled lowercase in order to be matched, but the default for Unredirect Match spells it Vlc. Totem works. firefox must also not be capitalized for it to match, but the default is for it to be capitalized.

Using this video, linked in the previous bug +1051802

https://www.youtube.com/watch?v=ZCPkOpMHB7g

It's possible to test whether a video is full-screen by enabling compiz effects, like Opacity (in which case the behaviour seems to be that if you try to initiate transparency while a window is fullscreen unredirected, it won't take effect until compositing turns on again, such as by moving the mouse to activate the menu in vlc) or, much easier, the Benchmark plugin, which shows a frames/sec overlay that disappears when a window goes fullscreen-unredirected.

When playing the test video in Firefox, occasionally when pausing, it actually shows a frame mid-tear, with the middle out of synch with the top and bottom. This is a completely unrelated issue though, since it still happens when pixels are being redirected (benchmark is displayed) and no tearing is occurring during playback.

Adding video players to the default matchings to exclude (! = not, for people like me who don't know programming languages) may have been the "fix" referenced in the previous bug report. The "impossible to fix" comment in that report seems accurate, it's probably an Nvidia bug.

It is still a little mystifying whether some Compiz options have any effect, like the vsync-related ones in Workarounds, but vlc and firefox being capitalized is a bug. The description of Composite > Unredirect Match suggests that "you might want to exclude video players, for example, to avoid tearing", but is this only because of a bug in Nvidia (or other graphics providers' configuration options)?

Not sure what the bug report submitter is using, but nvidia-settings has the option "Sync to Vblank", and "Allow Flipping". I found that turning off Allow Flipping leads to occasional tearing when recording video using  the x11grab device in ffmpeg, and 'Sync to Vblank' limits the framerate of the glxgears test program, but the description of Sync to Vblank is this:

"When enabled, OpenGL applications will swap buffers during the vertical retrace; this option is applied to OpenGL applications that are started after this option is set."

I'm not sure if this is supposed to apply to video playback. When a video player is being unredirected, I find that there is tearing and no other options will prevent it. 

When output is not being unredirected, I find that the only option that affects tearing is "Allow Flipping" in nvidia-settings. When it's on, there is no tearing. When it's off, there is always tearing. The following options seem to have no effect:

compiz:
OpenGL plugin:
Sync to VBlank
Framebuffer object
Vertex buffer object (this might just be a games thing, and I'm just testing video)
Always use buffer swapping

Workarounds plugin
Legacy Fullscreen Support (not completed tested with all other options combinations though)
Fix screen updates in XGL with fglrx
Force synchronization between X and GLX
Don't wait for video sync

I didn't completely test these:
Force complete redraw on initial damage
Force full screen redraws (buffer swap) on repaint

But they don't seem to prevent or cause tearing. They do show up when using the 'Show Repaint' plugin but require 'Vertex Buffer Object' option to be enabled.

in nvidia-settings, "Sync to Vblank" has no effect on tearing during video playback regardless of any other settings, even after the video player is restarted.

Ok, I guess maybe the answer to the question is that "vertical synch only works with buffers"?  I have no idea what other ways exist to swap buffers other than flipping, but that may be the issue here. Turning on Allow Flipping might prevent tearing in fullscreen applications like games, when Compiz isn't getting involved.

HOWEVER, I did most of that testing using totem. Tearing when unredirecting totem seems to be slightly worse than when it's redirected, and then swapped in by Compiz. With the nvidia-settings option "Allow Flipping" enabled, there is no tearing in totem with the default Compiz settings (where Totem is correctly capitalized), but there is tearing in vlc, which is incorrectly capitalized when it should be uncapitalized, as well as firefox with html5.

But when compiz is handling vlc's output, there's no tearing even with "Allow Flipping" disabled. It appears no combination of options will cause tearing in vlc, other than unredirecting output (by incorrectly spelling vlc as Vlc, which also requires "Unredirect Fullscreen Windows" to be enabled, both of which are the default settings).